The pyrolysis of vitrinite and inertinite by a combination of quantum chemistry calculation and thermogravimetry-mass spectrometry

Abstract

In this study, pyrolysis behaviour of vitrinite and inertinite from Heidaigou long-flame coal was studied via quantum chemical calculation and TG-MS. Quantum chemical calculation showed that vitrinite contains bonds with long bond length and small bond order, whereas inertinite revealed the opposite. And vitrinite and inertinite presented the same order of breaking bonds, but the numbers of breaking bonds showed differences. Before CO2 release, bond breakages and initial breakdown of macromolecular structure were observed. TG-MS analysis showed that the emissions with the same number of carbon, whether from vitrinite pyrolysis or inertinite pyrolysis, showed the same variation trend. Emissions from both vitrinite and inertinite can be divided into following four types. The first includes CO2, which was detected at 300 °C. The second consists of C1, C2, C3 and C4 compounds, which were observed at 420 °C and showed a fast release rate. The third comprises C6 and C7 compounds and CO, which were also detected at 420 °C with a slow release rate, and the fourth includes H2, which was identified at 500 °C. The escapes of the same substances during pyrolysis of vitrinite and inertinite were compared. Almost all emissions from vitrinite were higher than those from inertinite, but the temperature of maximum CO2 release from vitrinite was lower than that of inertinite.